Our previous research showed that the properties of both of these two functional sites (Ca2+-binding site and phosphorylation site) of the RLC can be significantly altered in the presence of cardiomyopathy-associated mutations in MYL2 (Szczesna et al., 2001; Szczesna-Cordary et al., 2004). This evidence concerns the gene MYL2 and cardiomyopathy.